Question 1

Which of the following best explains why only certain cells in the body respond to a specific hormone like epinephrine?

Accepted Answer

Only those cells have the specific receptor that binds epinephrine.

Question 2

During the 'fight or flight' response in an impala, which of the following sequences correctly describes the steps of cell signaling that lead to glycogen breakdown in muscle cells?

Accepted Answer

Reception → Transduction → Response

Question 3

Which type of chemical messenger is most likely to bind to an intracellular receptor and act as a transcription factor?

Accepted Answer

Steroid hormone

Question 4

A mutation prevents a G protein from hydrolyzing GTP to GDP. What is the most likely consequence for the cell signaling pathway?

Accepted Answer

The pathway will remain active longer than normal.

Question 5

Which of the following best describes the role of protein kinases in a phosphorylation cascade?

Accepted Answer

They transfer phosphate groups from ATP to proteins.

Question 6

Which of the following is a second messenger commonly involved in G protein-coupled receptor (GPCR) pathways?

Accepted Answer

cAMP

Question 7

What would most likely happen if a cell lacked sufficient ATP during a signal transduction cascade?

Accepted Answer

Protein kinases would not be able to phosphorylate target proteins.

Question 8

Which of the following is true about the amplification of a signal in a cell signaling pathway?

Accepted Answer

A single hormone molecule can lead to the production of millions of product molecules.

Question 9

Which of the following best describes paracrine signaling?

Accepted Answer

A cell releases local regulators that affect nearby target cells.

Question 10

Which of the following is a key difference between peptide and steroid hormones?

Accepted Answer

Peptide hormones bind to cell-surface receptors, while steroid hormones bind to intracellular receptors.

Question 11

Which of the following would most likely result from a nonfunctional phosphodiesterase enzyme in a cell?

Accepted Answer

cAMP levels would remain elevated, prolonging the cellular response.

Question 12

Which of the following best explains why the same hormone (such as epinephrine) can produce different responses in different cell types?

Accepted Answer

Different cells have different collections of receptors and internal proteins.

Question 13

Which of the following is the correct chemical equation for the conversion of ATP to cAMP by adenylyl cyclase?

Accepted Answer

$$\mathrm{ATP} \xrightarrow{	ext{adenylyl\ cyclase}} \mathrm{cAMP} + \mathrm{PP_i}$$

Question 14

A patient is given a drug that blocks all G protein-coupled receptors (GPCRs). Which of the following would most likely be an immediate effect?

Accepted Answer

Cells would be unable to respond to many hormones and neurotransmitters.

Question 15

Which of the following is a direct result of ligand binding to a ligand-gated ion channel receptor?

Accepted Answer

The channel opens, allowing specific ions to flow across the membrane.

Question 16

Which of the following best describes the function of protein phosphatases in cell signaling?

Accepted Answer

They remove phosphate groups from proteins, turning off the signal.

Question 17

In the context of diabetes, what is the primary role of insulin in regulating blood glucose levels?

Accepted Answer

It promotes the uptake of glucose into muscle and liver cells.

Question 18

Which of the following scenarios best illustrates the concept of signal amplification in a biological pathway?

Accepted Answer

A single epinephrine molecule triggers the release of millions of glucose molecules from glycogen.

Question 19

Which of the following is a likely outcome if a cell's ligand-gated ion channel receptor is mutated so that it cannot close?

Accepted Answer

Ions would continuously flow into or out of the cell, potentially disrupting cellular homeostasis.

Cell Communication and Signal Transduction

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